Context window exceeded at turn 23. Here's how I track token usage without a tokenizer.

A developer building an agent for the Hermes Agent Challenge encountered a context window overflow error at turn 23, with no warning or graceful handling before the API exception. To prevent future crashes, the engineer implemented token usage tracking without a tokenizer, enabling proactive monitoring of context consumption.

This is a submission for the Hermes Agent Challenge. My Hermes agent's context window fills up gradually. Each turn adds messages. Tool call results add more. After 23 turns, the API returned a context length error — with no warning, no graceful handling, just an exception in the middle of a synthesis step.